Pressure seated reversing valve



JaIL 22, 1952 s. c. TURKENKOPH ETAL 2,583,242

PRESSURE SEATED REVERSING vALvE:

Filed Aug. 16, 1950 4 Sheets-Sheet l 5 INVENToR.

' SYLVANUS C. 7' URKN/(o/v' BY cg- THOMAS EVANS Jan. 22, 1952 s. c.TURKl-:NKoPl-l ETAL 2,583,242

PRESSURE SEATED REVERSING VALVE Filed Aug. 16, 1950 4 Sheets-Sheet 2 vJNVENTOR. SYLVANUS C. TURKLWKP/ BY 3- THOMAS W4/V5 ATTORNEY Jan- 22,1952 s. c. TURKENKOPH r-:TAL 2,583,242

v PRESSURE SETED REVERSING VALVE Filed Aug. 16, v195o 4 sheets-sheer 5INVENTOR. SYLVANUS C.-7'URENKOPH BY & THOMAS V4/V5 ATTORNEY Jan. 22,1952 Filed Aug. 16, 1950 S. C. TURKENKOPH EI'AL PRESSURE SEATEDREVERSING VALVE 4 sneeis-sheet 4 5mm/vus c. Tamm/(OPH BY 9. THQ/m5 EVANSm ff/ar ATTORNEY Patented Jan. 22, 1952 UNITED "STATES PATENT OFFICE18c1ims. (c1. 121-465) This invention relates to fluid control valves,and relates in particular to control valves for reversible fluid motors,such as, for example, servo motors. This application is a continuationin part of our application for Fluid Control Valve, Serial No. 72,864,filed January 26, 1949, and now abandoned.

In valves of this type various constructions heretofore have beenemployed to utilize the pressure of thesupply fluid for maintaining theworking faces of the valvein sealing relation. Such arrangementsmaintain the valve working faces in sealing relation during the periodwhen uid is flowing through the valve, at which time a small leakagegenerally entails no serious disadvantage, but are not satisfactory whenthe valve is in closed position. Where the iluid under pressure foroperating the motor is supplied by a pump, they require that the pumpmaintain sufricient pressure to hold the valve working surfaces sealed,or that a pressure reservoir be provided. The latter obviously is notpossible without the provision of further complicated mechanisms wherethe pressure uid is a liquid. Furthermore, the application of linepresure against the working surfaces makes the valve hard to operate,and may necessitate the provision of further complicated mechanism tofacilitate operation of the valve. L

t is an object of the present invention to provide a control'valve for afluid motor or the like, wherein the Working surfaces of the valve aremaintained in sealing` relation in the closed or neutral position ofsaid valve by the differential l or back pressure exerted across theworking element of the motor.

Another object is the provision of a control valve for a reversibleservo-motor or the like in which the back pressure of the motor fluidregardless of its direction exerts a seating pressure on the valvesealing surfaces to prevent leakage through the valve.

Still another object is the provision of a control valve for areversible servo-motor or the like providing for flow through the valveof supply fluid, and exhaust fluid from either end of the motor. andwherein the fluid under the highest pressure exerts a seating pressureon the valve sealing surfaces to prevent leakage through the valve. Y

A further object of the invention is the provision of a control valve ofthis type wherein movement of the working element of the -motor under anegative load is prevented from.unseat ing the working surfaces of thevalve.

A furtherfobject .is .the provisionofa valve of thistype wherein thetotal force exerted by the differential pressure serving to hold thevalve workingV faces sealedis maintained ata small value to allow easyoperation of the valve.

In accordance with the present invention in a control valve and motorsystem of the type having relativelymovable valve members withcooperating sealing surfaces and ports in said surfaces arranged toprovide for forward orreverse flow of fluid to the motor and bypassingof uid around the motor in neutral position of the valve, there isprovided a seating pressure chamber and a pair of pressure seatingpassages in one of said valve members having one-way valves thereinallowing flow` into said chamber, the pressure seating passages vbeingin communication with the forward and reverse ports of the motor whenthe control valve is in fluid bypassing position to transmit the higherof the forward or reverse pressures across said valve member to saidchamber to hold said members in sealing engagement. By this arrangementthe motor back pressure holds the valve members in sealing engagementand prevents leakage of fluid from the motor and consequent creeping ofthe motor. This invention also eliminates the need for operating thepump against a high back pressure when not connected vto supply fluid tothe motor. If desired, a third pressure seating passage having a one-wayvalve therein may be provided, the third pressure seating passage beingin communication with the supply port when the valve is in fluidbypassing position tc 4hold the valve member seated in this position. Inthis arrangement, the highest pressurefwhether it be the supply pressureor the back pressure from either end of the motor, applies a pressure tohold the valve sealing surfaces in engagement. any other desired meansor arrangement may be provided for holding the valve members seatedwhile supplyingl fluid under pressure to the motor.

Where the control valve is employed for operating a fluid motor subjectto an oscillating or negative load, that is, to a load operating in thesame direction or augmenting the iiuid pressure, provision maybe made tothrottle the exhaust flow from the motor to prevent the development onthe intake side of the motor of a pressure so low that it will developan unseating force on the valve. This may be accomplished by theprovision in one or both of the supply lines of the motor of a one-wayvalve opening in the direction of supply flow to the motor and -athrottled bypass passage around the one-way valve. This serves. tothrottle the exhaust flow from the motor. This combined one-way valveand bypass is located downstream of the valve surfaces, that is, betweenthe valve surfaces and the motor. Or, the unseating action may beavoided by locating pressure seating passages in a non-rotating part ofthe valve and providing check valves therein opening'int'o the ooirimonpressure chamber which exerts a seating pressureon the valve. Or, instill another arrangement a single flow throttling restriction isprovided for carrying the exhaust from the motor, and suppiy passages inthe valve are arranged to bypass-A the restriction when supplying Iiuidto the `niotonwhile the exhaust from the motor passesfthr'ough therestriction. This eliminates the red Tora'check valve. The valve is madeeasier to operate'by' reducing contacting surfaces substantially toa,minimum, and equalizing fluid pressures on the exposed valve surfaces.For this purpose pressure equalizing passages` are connected to theseat` u ing pressure "chamber so Ttliat the' equalizing forces will act-under the -highest prevailing pressure. The invention is'applicable tovarious types of'valves involvingv 'sealing surfaces which slide incontact with each other.'

The invention will be 'described in greater detail in connection with'the''accompanyingV draw.- ings wherein' are shownpreferredr embodimentsof theinvention by waybfexample, and where- Figure 1 is a side viewshowing the valve housing in quarter section and! with parts ofthe valvehousing and 'valve barrell broken away;

Figure 2 is a partly' diagrammaticcross-section view taken onthe line2-2 of Figure 1;

Figure 3 vis an en'd elevation of the valve barrel looking in thedirectioniof the arrows 3--3- in Figure 1; 'l M Figure 4 is anendelevation of-a portion looking' in the direction of the arrows 4 4-in Figurel; v

Figure 5 is a view similar to Figure 2, showing the valve memberdisplaced'ninety degrees;

' Figure 6 asection taken on line 6-'-6-of. Figure3;

Figure 7 is a. section taken on line l-imof Figure 3 with parts brokenaway;

Figures 8`and 9 'arediagrammatic views explaining theoperation of theinvention;

Figure l0 is an end view of a modication;

Figure 11 is a section tak'en on line Il --I'I of Figure on an enlargedscale: Y

Figure y12 is a section taken on line I2-I2 of Figure 11 with movablevalve Aparts diagrammatically shown in dot-and-dash in neutral position;

Figure 13 is a View similar to Figure 12,` showing the' valve in forwardposition; l

Figure 14 is a view similar to Figure l2',- show ing the valve inreverse position;

Figure 15 is a' section of the valve member taken on line I5-I5'ofFigure 16;

Figure 16 is an end view of the valve member as seen from 'its seatingface, the seating ring being removed; and

Figure 17 is a section taken 011 line I'I--II of Figure 1o throughther/ane body.

Referring to the dra-wing, the control valve comprises an enclosingcylinder or jacketv I received between the ilan'ged heads 2 andSand-held in assembled relation by stay bolts 4- passing through theflanges of the heads, or'in any other suitable manner.' Suitablevgasketsor; sealing rings 5.l are provided to'pr'event leakageat.v thejoints of .the jacketand heads. "Afniovablevalve member consists of a,cylindrical stern 8, an enlarged or barrel portion 9, and a stub portionIU. Stem 8 passes through a bore I2 in the head 2 and has a packing ringin a circumferential groove to provide a sealed connection therewith.The stem has a squared portion I3 on its end adapted to receive a wrenchor handle (not shown) for turning the valve member and the wrench may beheld in place by a nut (not shown) threaded on the cylindrical threadedend I4. Av suitable stop member I5 may be provided to limitl the"extremes of angular movement of the valve member tofabout 90. The stubportion I8 is received in a` guide bore I B in the head 3 c and may beprovided with a sealing ring.

' The enlarged valve barrel portion 9 has a middle circumferentialgroove I8 which is located to register with the threaded fluid pressureinlet or opening I9 in the jacket, and sealing rings 2I, 22 maybeprovided in suitable grooves on either side of the middle groove I8 tocooperate with jacket I and-prevent leakage of fluid from groove I8along the barrel towardthe ends. The barrel has a supply bore ordistribution passage 23 extending axially and-'ecc'entrically thereof,and a radial-bore or duct 2v4con'nectsannular groove I 8 therewith. Inneutral position of the valve the axial supply bore23registers with anaxial eccentrically locatedbypass bore or passageway 25 in the head 3,assliown in- Figure 1, which in turn is connected by a pressureequalizing bore 26 with the guide bore I Ii'.

A backing plate Z-'I-isreceived in the annular space 29a boundedby thevalve stem 8, valve barrel 9, jacket I and head 2. The backing plate isof less length than annular space 29a and is held spaced suiicientlyfrom head 2 by springs 3l) to provide a luid'pressure-chamber 29therebetween. Springs 30are` received in recesses 3| in the head 2landare guided by posts 32 secured in a face of the backing plate. Thegroundvface 33 of the backing plate is held against the ground face 34of the valve barrel-and 'the ground face 35 of the valve barrel isinturn held against C' ground face 3650i the head 3 by the pressure of theannular series ofhelical springs 3U. In the position of the parts shownin Figure 1, fluid under pressure which enters inlet I9 inthe jacketflows from annular groove I8 and duct 24 to supply bore 23-and bypass 25back to the pump through a suitable external tube or conduit (not shown)connected at threaded socket 3l' in the head 3 so that in this positionthe fluid is merely circulatedwithout operating the servo-motor.

The supply bore 23vin valve barrel 9 in cooperation with suitablepassages inv head3 provides for directing luidunder pressure to eitherend of the hydraulic cylinder or servo-motor, depending on whichdirection the valvebarrel is rotated. For this purpose, the internalface 36-of the head-3 has symmetrically located openings or passageways43 and 44 (Figures 2 .and7) on opposite sides'of passageway .25'.Passageway 43 connects with a tappedsocket 45 (Figures2 and 5) in thesurface of head 3A adapted. to receive a conduit 46- connected to oneend of the servo-motor 4l (Figures Band-9) while the tapped socket 48 inhead 3- at the end' of passageway 44 reecives a conduit 49 conne'ctedtothe other end of the servo-motor cylinder. Thus, by rotating the valvebarrel about 45 clockwsefromthe neutral position'as viewedin Figure 3 tothe position shown in dotted lines in Figure 2, the V,distributionpassageway '23.is brought intaregistrationwith passageway. .43,Ito.,.supp1y..ud. underpressure to shown in Figures 2 andere barrel about45 counter-clockwise from neutral position to the position shown indotted lines in 'Figure 5, the distribution passageway 23 is brought inalignment with passageway 44 to supply fluid under pressure to the otherend of the servo-motor cylinder by way of passage 44 and conduit 49. Forclarity, the passageway 23' is and as a reduced diameter bore. n1irovision is also made in the valve so that when viluid under pressureis supplied to one end of the servo-motor cylinder, the fluid on theother side or the pistonV in the servo-motorlcylinder may be exhaustedthrough the valve and returned to the pump or reservoir. The head 3 hastwo longitudinal bores 5l and 52 interrupting the faceSB which areinterconnected by internal crossed bores or passages 53, 59 and 55 tothe passageway leading back to the pump. The face 35 of the valve barrelhas two elongated blind grooves or culs-de-sao 56, 51 so located thatwhen the valve barrel is turned clockwise as seen in vnection 59,passage 44, cul-de-sac 55, passageway 52 and crossed bores 55, 54 to thecommon return 25 and thence to thepump. Conversely, Awhen the valvebarrel is turned counter-clockwise toalign passageways 23 and 44 asshown in Figure 5, the return iiuid or exhaust from the servo-motorentering at 45 iiows through passageway 413, cul-de-sac 51, passage 5iand crossed bores 53, 59 to common return 25.

The valve structure embodies provision for applying the back pressure ofeither end of the servo-motor cylinder to press ground or lapped face 35of the valve against ground or lapped face 35 o1 the head to preventloss of pressure from the operating side of theV servo-motor cylinder,and thus prevent creeping of the servornotor piston and `of appliancesattached thereto. Springs 3@ provide an initial bias to hold therespective faces or" barrel 9 in engagement with the i'ace 33 (Figure l)of backing plate 21 and face 3S of head 3. Back pressurepassages 6| and52 (Figures 4 and '1) extend through backing plate 21 from face to face,and in neutral position of the valve, passages 5l and 62 arein alignmentwith axially extending back pressure passages t4 and S3 respectively inthe valve barrel. Each passage 63 and 64 has a one-way or check valvetherein opening in the same direction, and as the two check valves arealike, the construction of only one check valve wi11 be de scribed indetail. Passage 63 (Figure 1) contains a .sleeve 65, the end of whichserves as a seat for the ball 39 held in engagement therewith by aspring d1 abutting an enclosing sleeve 58. As the backing plate 21 doesnot rotate, it may be regarded as part of the housing.

Assuming power has been supplied to the servornotor through connection44, when the valve barrel is returned to neutral Vposition back pres-Sure passage 53 is in alignment with supply'passage 4e to the motor andpassage 62 in plate 21. AThe Vtrapped pressure in the servo-motor cyl-'inder developed by the appliance connected to the piston is`transmitted from passage 44' through 'to hold the valve faces lnengagement. lvalves 66 are arranged to allow flow into pressure thecheck valve in passage 63 and through passage 52 to chamber 29, andexerts a pressure in chamber 29 on the-plate 21 and the valve barrel tokeep the-faces of valve barrel `9 in sealing engagement with the facesof Lbacking ring 21 and `valve head 3,'thus preventing leakage betweenrthe lapped or ground mating faces thereof. rlrhe chamber on theopposite side of the servo-motor piston also is connected to pressurechamber 29 by passages 43, 54 and 6l, so that if the appliance connectedto the servo-motor 'piston exerts a 'force in theopposite direction, thefluid pressure from the other chamber of the motor is transmitted bypassages43, 64 and 6l to chamber 29 The check chamber 29 and preventIiow out of this chamber, and thus prevent short-circuiting of the iiuidbetween the passages 43, 44 leadingto opposite sides of the motorpiston. If desired, the check valves may-be located in the passages BI,92 in the backing plate. l Y

The high pressures encountered under some conditions may make thecontrol valve diiiicult to rotate, because of the frictional contact ofthe sealing or mating surfaces of the valve barrel. We prefer to reducethe contacting surfaces to a minimum by cutting back or relieving thesurfacesBd and 35 oi the valve barrel adjacent the periphery of thebarrel and adjacent thestem. Resistance to turning may be furtherreduced by more or less counterbalancing the pressure effect on thevalve barrel. VFor this purpose the valve has an axial bore orpassageway 1| connected to the pressure chamber 29 by a radial bore 12.inclined or radial bores 13 and 14 connect the relieved portions,recesses or grooves 15. 1B in the valve face with `the bore 1 i, andradial grooves or recesses 11 lin each face of the valve barrel connectthe relieved grooves or recesses 15, 15 with the circumferentialrelieved areas 18 and 19 respectively. As all the relieved areas areconnected to a common source of pressure, namely the chamber 29, theliuid pressures on these areas are directionally balanced. Thus, theaxial force exerted by pressure plate 21 on the valve barrel is the unitpressure in chamber 29 times the contact area of one valve barrel face,plus the spring pressure, because on all other areas of the valve thefluid pressure is counterbalanced.

It sometimes happens during operation of the servo-motor, as forexample,when operating a plow lift on a tractor, that the weight of the plow andthe burrowing of the plow into the earth as the tractor advances causesthe servomotor piston to displace more volume than the quantity ofpressure iiuid supplied thereto, and this develops a vacuum on theworking side of the servo-motor. That is, the piston tends to movefaster than the fluid can iill the chamber. Under such conditions withthe construction illustrated, as for example, with the distribution'passage 23 in alignment with both supply passac 5'! to unseat the valvesealing surfaces and cause bypassing of iiuid from passage 43 to passagee4, which causes the servo-motor to advance lwith a sudden jerk orjolt.` This maybe avoided .by providing a combined one-way valveand'bypass in one 'exhaust line upstream of the valve described.

tion between socket 4 5 and the servo-motor.

Figures 8 and 9 diagrammatically illustrate thisarrangement applied to aslide valve in which the one-way valve 8| in the position shown inFigure 9, compels exhaust uid from the servomotor cylinder to flowthrough -the bypass 82 whichrestricts exhaust vflow from that side yofthe motor to a rate such that the plow cannot force the piston againstthe resistance of the bypass fast enough to create a vacuum ontheWorking side. Thedanger of unseating the lvalve barrel thus iseliminated.

The operation of the invention will be further described in connection.with .the diagramsl in Figures. 8, and 9 illustrating a rectilinearoperating or slidevalve embodying the invention, Vand wherein likepartsare indicated by like reference numerals. When the valve is movedto operating position at the left as shown in Figure 9, the distributionduct or port. 23 is ,connected to the motor chamber passage 44 and theconduit 49, and the exhaust ows through conduit 45 and through bypass32, passage 43, cul-de-sac 51, passage and bore 53 to the common return25. The check valve 8| prevents direct flow through passage 43, and thebypass 82 provides a suflicient restriction so that the pull of theplow, or other device con- -nected thereto, to the right on the pistonof the servo-motor, must force uid through the bypass. This retards themovement of the piston suffi- .ciently to prevent the development of avacuum .inchamber 29 which is connected through passages 02, 23 to thesupply side of the motor chamber', and prevents unseating of the valve.

We have shown check valves and bypasses 8|, 82 in both exhaust lines ofthe motor, but it will be. understood that they may be omitted fromeither or both lines where. the vacuum-producing condition is notencountered.

When the servo-motor has reachedv the desired position the valve barrel9 is returned to the neutral position shown in Figure 8. In thisposition the respective chambersr at the ends of the servomotor pistonare connected through passages 43,

63, 5| and fifi, 64, .S2 respectively with the cham.-

. ber 29.` rlhus, thev pressure at either end of the servo-motor piston(whichever end is higher) is transmitted to chamber 2S to exert aseating pressure on the valve faces, and thus prevent separation of thevalve seating faces and consequent leakage of fluid from theservo-motorr chambers. As the seating vfaces are accurately ground orlapped, no leakage can occur from the motor chambers as long` as theseating surfaces are in I contact in such position or in the,non-operating for neutral' position can be maintained by any f othermechanical or hydraulic arrangement desired. The abutment plate 21 maybe omitted. if desired, by a rearrangement of valve ports and passages.One such rearrangement now will be Referring to Figures to 17, thecylindrical valve body 85 has a uid` supply tap'86 connected byslopinginternal passageways v81 and '88 (Figures ;12to 14) to vaxiallyextending ports 89 and9| which openA at the seating face 92 of the body(Figures 11 and 17). Pipe taps 93 and 94 in the body each connect fromone side of the motor il (Figure 9) to ports S5 and 96 opening into theseating face. In order to render the explanation of the operation of thevalve more simple, tap 93 will be considered as the forward connectionto the motor and tap 94 as the reverse connection. Inthe constructionillustrated, thecenters of taps 86, 93 and 94 are in one plane towardthe rear or right of vthe body, as seen in Figure 1'1, and the ports 89,9| 95, and S6 are drilled in deep enough to connect with the radialbores extending from these taps. The threaded exhaust or bypass bore 91extending coaxially of the body connects with the crossing bores 98, 9S,|00, and |0| which respectively connect with axial ports |02, |03, |04,and |05 opening into the seating face 92. Port |05 receives a bushing|06 with a pressed t that has a small opening |01 therein, so that flowthrough this port is restricted. If desired, a similar restrictingbushing can be positioned also in port |04. Bores 08 to |0| are all in acommon plane to the left cf taps 36, 93, and 94 (Figure 11), and therespective ports |02 to |05 are drilled 'the proper depth to connecttherewith without intersecting the taps.

A cylindrical housing |08 has one end closed by body and the other endis covered by triangular plate |023 in liquid-tight relation, thusproviding a vaive seating pressure chamber A valve operating stem ||2passes through bore H3 in the triangular top plate through a packing,and a movable valve disc or plate ||4 is connected to be operated by thestem through a keyand-slot connection H5. The valve disc has. a hardenedring I8 providing a seating surface l1 engaging the seating surface 92of the body, but as this ring ||8 may be integral with the valve discits face |1 will be so considered as part of the disc I4 to simplify thedescription. A spring HB abutting the valve disc and a thrust washer i9holds the valve disc on its seat. An adequate clearance is providedbetween the housingv |08 and the periphery of the valve.v

Referring to Figure 16, there are three arcuate pockets |2|, |22, and|23 formed in the seating face |11 of the disc. Referring to Figure 12,the uid lines to and from the servo-motor connect by taps 93 and 94 toports 95 and 96 respectively. In neutral or motor bypass position of thevalve disc, pockets 2| and |22 connect supply ports 89. 9| with ports|82 and |03 connecting; by radial passages 98 and 99 with central bypasstap 91. In this position liquid supplied to the valve at tap 85 merelybypasses the motor, and in flowing through the valve divided into twostreams, one stream ilowing through passage 81, bore 89, pocket 2|, bore|02 and passage 98 to return passage S1; and the other stream owingthrough passage 83, bore 3|, pocket |22, bore 03y and passage 99 toreturn passage 91, which returns to the pump. The pocket |23 connectsports |04 and |05, but as these ports are connected to the bypass bore91 by radialV bores |00 and |0| respectively, the pocket |23 serves nofunction in this position.

When the valve disc I4 is turned counter.- clockwise to the positionshown in Figure 13, the pocket |2| connects supply port 89 with port 95connected to forward tap. 93 to the motor. The exhaust from the motorenters by tap 84, and as .pocket |23 connects port 95 with port |04connected. to exhaust borev |00, areturn path for the motor exhaust isprovided. In this `position pocket |22 connects exhaust ports |92` and|03 and has no function.

Similarly, when the valve disc is turned clockwise to the position shownin Figure 14, pocket |2| idles across ports |02, |03, and pocket |22connects supply port 9| to motor reverse port 93. The exhaust from themotor enters attap A93, and pocket |23 connects port 95 to restrictedport |05, which connects by orifice |01 to the exhaust passage 91.Orifice |01 thus restricts the flow of exhaust fluid from the motor, inreverse position, but does not-function las a restriction in forwardposition,

Referring to Figure 14, it will be seen that the exhaust from the motoriiows from tap 93 and port 95 through pocket |23, AVthen throughrestriction |01 in port |05 to the exhaust passages and 91. Thisrestriction |01 throttles the exhaust flow from the motor so that wherea negative load develops on the motor it is not possible for the supplypressure at the valve face pocket |22 to fall so low as to develop anunseating force on the valve.

The periphery of valve disc I |4 has three radial .f bores |25, |23, and|21 (Figure 16) which are` counterbored at |28, |29,l and to provideseats for the ball valves |3|, |32 and |33. A garter spring |34 isreceived in a circumferential groove |35 around the valve to hold theballs on their seats. Pocket |22 has a radial groove |3o` connectingwith an axial bore |31 that extends to bore |26. The valve face has acircular bore or pocket |38 located between pockets |2|, |23, and asimilar circular pocket |39 islocated between pockets |22, |23. A radialgroove iM extending from pocket 38 joins an axial bore |42 that connectswith bore |25, and a radial groove |43 extending from pocket |39 joinsan axial bore |44 that connects with bore |21. Ball valves |3| to |33allow flow of fluid radially outward toward the periphery of the valvedisc, and through the clearance at the disc periphery into chamber lll,but do not allow escape of uid from chamber v Referring to Figures l2and 16, when the valve is in neutral position ball valve |32 connects bypassages |29, |31, and |35 to pocket |22 which is connected by port 9|and passage 88 to supply tap 89. In this position supply pressure canescape past ball |32 into chamber to hold the valve disc H4 on its seat.Ball valve |33 connects by passages |21, |44, |43 and pocket |39 withport 93, and ball valve |3| connects by passages |25, |42, |4| andpocket |38 with port 35. Thus the highest pressure, whether it be thesupply pressure at tap 86, or the back pressure of the motor at taps 93,94, will be applied through the respective ball valves to the chamber ll to maintain the valve disc on its seat.

In the forward position shown in Figure 13, ball valve |33 is connectedby pocket |39 to port 9| which is in turn connected to supply tap 85;ball valve |32 is connected by pocket |22 with the exhaust pressure sideof the motor by its connection to port |03, passages 99, |00, pocket |23and bore 95. Therefore, in this position also the chamber is subjectedto the higher pressure, whether that be the motor supply pressure or theexhaust pressure. In the forward position shown in Figure 14, ball valve|3| is connected by pocket |38 to the supply port 89, and ball valve |32is connected to the supply pressure through the motor supply port 96.Ball valve |33 is connected to the motor exhaust through pocket 10 |39and port |04 so that again the chamber is subject to the higherpressure, whether that be the motor supply or exhaust pressure.

This construction is of special utility where the motor is subject tofluctuations in force, as for example, where the motor is used to raiseor lower a plow or other earth-working tool on a tractor. In suchexample, when the tool is in raised position and the tractor jostlesover rough ground, the tool will be jolted, thus applying a momentaryvhigh force on the motor in either direction. With this arrangement thehighest pressure is transmitted to chamber to keep the valve discseated, and thus leakage at the seat is prevented. This prevents creepof the motor.

We claim asour invention:`

l. A control valve for a fluid motor, comprisrelatively movable members,having cooperating sealing surfaces having ports in said surfacesarranged to provide forward and reverse fluid passages anda bypass forfluid, lone of said members having a pair of back pressure passages,means forming a chamber exerting pressure on one of said members, thesaid back pressure passages communicating with the chamber, one-wayvalves in the back pressure passages allowing uid ilow into said chamberand being in communication with the forward and reverse ports when thevalve is in uid bypassing condition to transmit forward and reversedifferential pressures across said members to said chamber to hold saidmembers in engagement.

2. In a control system for a reversible fluid motor, the combinationcomprising, a control valve including relatively movable members havingcooperating sealing surfaces and having ports in said surfaces, meansforming a chamber communicating with the ports and exerting pressure onone of said members, said ports being operatively arranged to providereverse and forward fluid passages and a bypass for uid around a fluidmotor, one of said members having a pair of back pressure passagesconnected to said motor when the control valve is in bypassing conditionto apply the back pressure of the motor to said chamber for pressing theworking surfaces of said members together, and one-way valve means inthe back pressure passages to allow ow of pressure uid from the motorinto said chamber.

3. A control valve for a fluid motor, comprising a cylindrical housingincluding a head having a pair of supply ports, adapted to be connectedto a fluid motor, and an intermediate bypass port, the said headhavingalso a pair of exhaust ports interconnected withsaid bypass port,a rotatable valve barrel having an axially extending passage `adapted tobe selectively connected with said bypass port and supply ports, saidvalve 'barrel having recesses for selectively connecting one supply portto an exhaust port when V'said axial passage communicates with the othersupply port, means forming a chamber at one endof the barrel, and thevalve barrel having back pressure ports located to supply back pressurefrom said supply ports to the chamber, said back `pressure ports havingone-Way valve means therein allowing ow into said chamber whereby thepressure in said chamber holds the valve barrel 4seated on said head.

4. A control valve for a fluid motor, comprising a cylindrical housingincluding a head having a pair of supply ports, adapted to beconnectedto a fluidV motor, and an intermediate bypass port, the saidhead having also a pair of exhaust ports interconnected with said bypassport, a rotatable `valve barrel having an axially extending passageadapted to be selectively connected with said .bypass lport andsupplyrports, said valve barrel having recesses for selectivelyconnecting one supply port to an exhaust port when said axial Ypassagecommunicates with the other supply port, means forming a chamber at oneend of the barrel, the valve barrel having back pressure ports locatedto supply back pressure from said supply ports to `the chamber, saidback pressure ports having one-way valve means therein allowing liowinto ksaidchamber whereby the pressure ,in said chamber holds the valvebarrel seated on said head, a backing plate for the valve barrel, springVmeans engaging the plate to urge said barrel against said head, and theplate having passages registering With the back pressure ports in thefluid bypassing condition of the valve.

5. A control valve for a fluid motor, comprising a cylindrical housinghaving a pair of heads, one of said heads having supply ports adapted tobe connected to a fluid motor and a bypass port adapted to be connectedback to a pressure source, said head also having exhaust portsinterconnected with said bypass port, a rototable valve barrel betweensaid heads and having recessed faces, a thrust ring between said valvebarrel and the other of said heads and providing a pressure chamber withsaid head, resilient means in said chamber for maintaining thecontacting surfaces of said ring, barrel and ported head in engagement,said valve barrel having an axial supply vpassage for selectiveconnection with said supply ports and bypass port, the barrel alsohaving re- .cesses .for lselectively connecting an exhaust port with va.supply port and having back pressure portsfor registering with saidsupply ports, said back Apressure .ports having one-way valve means.therein allowing flow into said pressure chamber, .and ,said thrust`ring having passages therethrough registering with said back pressureports.

6. A control valve for a iiuid m-otor, comprising la cylindrical housinghaving a pair of heads, `one of s aid heads having supply ports adaptedto :be connected to a fluid motor and a bypass portl .adaptedfto beconnected back to a pressure source, said head also having exhaust portsinterconnected Ywith said bypass port, a rotatable valve ,barrel betweensaid heads and having recessed faces, a thrust ring betweensaid valvebarrel and y-theother of said heads and providing a pressure chamberwith said head, resilient means in said ,chamber for maintaining thecontacting surfaces of said ring, barrel and ported vhead in engagement,said valve barrel having an `axial supply passage foriselectiveconnection with said supply ports and bypass port, the barrel havingrecesses for selectively .Connecting an exhaust port with a .supply portand having back pressure ports for registering with said supply ports,said back pressure ports having one-way valve means therein lallowinglflow `into said pressure chamber, said ythrustring having passagestherethrough registering with said back pressure ports, and the barrelhaving passages connecting the pressure chamberl with the recesses inthe barrel faces to .balance the pressure thrust on the barrel.

7. A control valve for a fluid motor, comprising ,a'cylindrica'l housinghaving a ported head and a blank head, said ported head having supplyIports adapted to be connected to a fluid `motor .and a :bypassportadapted to vbe connected back to apressure source and exhaust portsinterconnected with said bypass port, a rotatable valve;

.barrel in said housingspaced from the'blank head to provide a pressurechamber therebetween, means resiliently pressing 'a face of said barrelagainst said ported head, said barrel having a ,pair of recesses forinterconnecting said supply ports and exhaust ports and a pair of backpressure ports for connecting said pressure chamber .with VSupply ports,and the said back pressure vports having one-way valves therein allowinguid iiow into the chamber.

8. Acontrol system Vfor a fluid motor, comprising ,a .Valve includingrelatively movable members with cooperating sealing surfaces and having.ports in said surfaces arranged to provide a supply passage and forwardand reverse fluid passages to the motor chamber and a bypass for huid,said valve having a pressure chamber lo cated .to exert pressure on oneof said members .to maintainsaid sealing surfaces in engagement, -saidpressure .chamber being in communication withsaid supply passage whenthe supply passage lis in position to Vcommunicate with the respectiveforward and .reverse fluid passages to -the motor, acne-way valve ineach forward and .reverse passage between the supply passage and themotor chamber, means forming a restricted bypass passage around eachsaid one-way valve, and Athe .one-way valve allowing fluid flow throughthe forward and reverse passages to the motor chamber compellingdischarge of fluid from the motor .chamber through the restrictedbypass.

9. A control system for a .fluid motor, comprising a valve includingrelatively movable members with engaged ycooperating sealing surfacesand having'ports in said surfaces arranged to provide a supply passageand forward and reverse fluid passages to the motor chamber and a bypassfor fluid, means v,forming a pressure chamber located .to exert guidpressure on one of said members, one of said members having a pair ofback pressure passages communicating with the pressure chamber to4lmaintain said sealing surfaces in engagement, a one-way valve in eachback pressure passage allowing huid flow into said pressure chamber fromthe motor when the respective back :pressure passages areincommunication with said forward and reverse fluid passages, saidpressure chamber-beingiin communication with said supply passage whenthe ysupply passage is in position to communicate with the respectiveforward and reverse fluid passages to the motor, a one-way valve in eachforward and reverse passage between `the supply passage and the motorchamber and .means Aforming a restricted by es@ passage around eachlatter one-way valve, said one-way valve-in 'eachvforward and reversepassage allowing fluid iow through the forward and reverse passages toythe motor chamber and compelling discharge of fluid from the motorchamber through the restricted bypass.

10. 'A control valvefor a fluid motor, cenriprisingr relatively movablemembers with cooperating' sealing surfaces and having ports in said sur-'faces arranged to provide a supply passage and fforward and reverse andexhaust'iluid passages,

said valve having a pressure chamber located to exert fluid pressure onone of said members to maintain said sealing surfaces in engagement,said pressure vchamber being in communication with said -supplypassagewhen the supply passage is in position` to communicate with therespective forward and reverse fluid passages to the motor, one of ysaidpassages having a restriction therein, and one of said members having apassage therein sealing surfaces and having ports in said surfacesVproviding supply and forward and reverse fluid passages, said valvehaving a pressure chamber located to exert fluid pressure on one of saidmembers to maintain said sealing surfaces in engagement, the said valvemembers having pressure passages communicating said pressure chamberwith the forward, reverse, and supply fluid passages, and a one-Wayvalve in each pressure passage to allow flow of fluid into said pressurechamber.

12. A control valve for a fluid motor, compris- 14 Y pass passage'forfluid, the valve having a iluid pressure chamber located to exert fluidpressure on one of the valve members to hold said sealing surfaces inengagement, the valve having a plurality of back pressure ductsconnecting said fluid passages and having one-way valves therein to ingrelatively movable members with cooperating i sealing surfaces andhaving ports in said surfaces providing supply and exhaust fluidpassages, said valve having a pressure chamber located to exert uidpressure on one of said members to maintain said sealing surfaces inengagement, a oneway Valve connecting the said pressure chamber withsaid supply passage, means forming a restriction in one exhaust passage,the said valve members providing a fluid flow passage bypassing therestriction when supplying fluid to one exhaust passage, and connectingsaid restriction into an exhaust passage when supplying fluid to anotherexhaust passage.

13. A control valve for a fluid motor, comprising relatively movablemembers with cooperating sealing surfaces and having ports in saidsurfaces providing forward and reverse passages and a return passage forfluid, means forming a fluid pressure chamber located to exert fluidpressure on one of the valve members to hold said sealing surfaces inengagement, and means forming a plurality of back pressure ductsconnecting with at least two of said fluid passages and having onewayvalves therein to allow flow into said pressure chamber.

14. A control Vvalve for a fluid motor, comprising relatively movablemembers with cooperating sealing surfaces and having ports in saidsurfaces providing supply and exhaust passages, means forming a fluidpressure chamber located to exert fluid pressure on one of the valvemembers to hold said sealing surfaces in engagement, means forming apair of back pressure ducts connecting with said fluid passages andhaving oneway valves therein to allow flow into said pressure chamber,at least one of said passages having a restriction therein, and at leastone of the passages in one of the movable members consecting saidrestriction with an exhaust passage or selectively bypassing therestriction.

15. A control valve for a iluid motor, comprising relatively movablemembers with cooperating sealing surfaces and having ports in saidsurfaces providing forward and reverse passages and a byallow flow intosaid pressure chamber, means forming a restriction in at least one ofthe forward and reverse passages, and one of said members having apassage bypassing the restriction.

16. A control valve for a fluid motor, comprising a ported valve plate.a movable valve member having a surface in sealing engagement with fsaid plate and having distributing passages for forward, reverse andbypass passage of fluid, means forming a pressure chamber surroundingsaid movable valve member, and the movable valve member having aplurality of ducts and having one-way valves in the ducts allowing flowinto said chamber, said ducts being connected to the forward, reverseand bypass passages, respectively.

17. A control valve for a fluid motor comprising a housing having apressure chamber'and a ported valve face, a movable valve member in saidchamber having a face in sealing engagement with the rst face and havingports therein, the valve member having a plurality of radial passagesand said passages having one-way valves therein connecting said portswith the pressure chamber, and means biasing said one-way valves toclosed position.

18. A control valve for a fluid motor, comprising relatively movablemembers with cooperating sealing surfaces and having ports in saidsurfaces providing a supply passage and an alternative supply or exhaustpassage for fluid, the valve having a fluid pressure chamber located toexert fluid pressure on one of the valve members to hold said sealingsurfaces in engagement, and the valve having a pair of back pressureducts connecting with said supply and alternative passages, each ducthaving a one-way valve therein to allow flow into said pressure chamber.

SYLVANUS- C. TURIENKOPH. THOMAS EVANS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 870,104 Holden Nov. 5, 1907905,605 Tarn Dec. 1, 1908 FOREIGN PATENTS Number Country Date 14,666Great Britain of 1897

